Magnetometers using a SQUID(Superconducting QUantum Interference Device) have been known. These magnetometers have very excellent sensitivity and response and they are used in the field of high precession and high sensitive measurements. By means of the magnetometer using the SQUID, weak magnetic filed signals produced from a human body can be detected and geographical surveys such as searches for oil reservoirs, high-temperature water reservoirs, etc. can be carried out with high precision.
The magnetometers have a flux detecting coil(pick-up coil) for catching signal flux. This caught flux is fed to the SQUID which is magnetically coupled with a superconducting loop including the detecting coil.
Due to the inductance of the superconducting loop including the detecting coil for catching the signal flux, there is an unresolved problem that the high-sensitive and high-response characteristics of the SQUID have not fully been used.